The present invention is directed to a differential pressure switch having a Hall effect sensor located in a sensor chamber for detecting the position of a magnet coupled to a flexible diaphragm that separates a low-pressure fluid chamber from a high-pressure fluid chamber, and in particular to a differential pressure switch wherein the Hall effect sensor and the sensor chamber are isolated and sealed fluid-tight from the low and high-pressure fluid chambers by an integrally-formed non-perforate wall.
Differential pressure switches such as disclosed in U.S. Pat. No. 3,566,060 include a diaphragm located between a low-pressure fluid chamber and a high-pressure fluid chamber. A mechanical switch is located in a switch chamber that is separated from the low-pressure fluid chamber by a separating wall. However, the separating wall includes an aperture through which the switch is mechanically coupled to the diaphragm, such that the fluid within the low-pressure fluid chamber is in contact with the mechanical switch. Any mechanical or adhesive seal between the switch and the separating wall can also leak and allow fluid to enter the switch chamber. The mechanical switch includes electrical contacts that can ignite the flammable fluid from the low-pressure chamber and cause an explosion.
The present invention enables the position of the diaphragm to be monitored by a sensor and other electrically operated components located in a sensor chamber that is sealed in fluid-tight isolation from the low and high-pressure fluid chambers by a one-piece non-perforate partition wall such that fluid within the low and high-pressure fluid chambers cannot come into contact with the electrical components of the switch and cause an explosion.